Tried playing a game with my SO via Remote Play Together; invite and join worked, but their screen appeared to be flickering between my view and what I assume would have been their view; they generally couldn't interact with the game. Not having tried this other than with these Steam Decks, I'm not sure what's normal and what isn't; i.e. I don't know how it would normally work: at least in this game, it appears that Remote Play Together is only ever a Shared/Split Screen PVP or Co-Op, but at least based on my experience it was trying to do Shared and Split screen at the same time: I don't know how much of that is the game, how much is Proton, etc, and how much is Remote Play Togher.